In Depth:Sinus Cavities

There are four pairs of sinuses (named for the skull bones in which they are
located):

Frontal sinuses:
The right and left frontal sinuses are located in the center of the
forehead (frontal bone) just above each eye.

Maxillary sinuses:
These are the largest of the sinuses and are located behind the cheekbones
near the maxillae, or upper jaws.

Sphenoid sinuses: The
sphenoid sinuses are located in the sphenoid bone near the optic nerve and
the pituitary gland on the side of the skull.

Ethmoid sinuses:
The ethmoid sinuses are located in the ethmoid bone, which separates the
nasal cavity from the brain. These sinuses are not single sacs but a
collection of six to 12 small air cells that open independently into the
nasal cavity. They are divided into front, middle, and rear groups.

Like the nasal cavity, the sinuses are all lined with mucus. The mucus
secretions produced in the sinuses are continually being swept into the nose by
the hair-like structures (called ‘cilia’) on the surface of the respiratory
membrane.

When they aren’t moistening the air we breathe through our noses, the hollow
sinuses act to lighten the bones of the skull. Sinuses also serve as sound-resonance
chambers for speech.

The paired and often asymmetrical (not perfectly mirrored) sinuses are small,
or rudimentary, at birth but grow as the skull grows. They are fairly well
developed by age seven or eight, but don’t reach their maximum size until after
puberty. In adults, the sinuses vary considerably in size and shape.

Sinuses often get infections. Sinusitis is
inflammation of a sinus caused by a bacterial infection that can follow a viral
infection. This causes pus and mucus to accumulate in the sinus. Symptoms can
include fever, headache, stuffy nose, and impaired sense of smell.

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